AB0828 THE DIAGNOSTIC AND PROGNOSTIC VALUE OF COMMERCIAL LINE BLOT ASSAY IN TAIWANESE PATIENTS WITH SYSTEMIC SCLEROSIS
Authors: T. H. Yen, W. N. Huang, Y. M. Chen
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Emerging evidence has demonstrated the clinical utility of scleroderma-specific autoantibodies in systemic sclerosis (SSc) <sup>[1]</sup>. However, the diagnostic performance and prognostic value of line bot assay (LIA) in Taiwanese patients was unknown. <h3>Objectives</h3> Our aim is to evaluate the diagnostic performance of a commercial LIA and the prognostic value of SSc-specific antibodies and anti-Ro52 in Taiwanese population. <h3>Methods</h3> We retrospectively enrolled all individuals tested by the LIA with 13 antigens between 2020 and 2021 in Taichung Veterans General Hospital. The diagnosis of the scleroderma was based on the 2013 ACR/EULAR classification criteria. The positive result of the semi-quantitative test was presented as +, ++ and +++ based on the signal intensity. If multiple antibodies were detected, the patient will be categorized according to the antibody with the highest signal intensity. Multivariable logistic regression was used to evaluate the association between autoantibody subtype and clinical phenotype. <h3>Results</h3> A total of 896 patients (209 SSc, 293 non-SSc CTD, 394 non-CTD) were retrospectively analyzed. ROC analysis of LIA showed numerically higher AUC excluding anti-Ro52 in comparison with whole panel. After excluding anti-Ro52, the LIA exhibited sensitivities of 79.9%, 65.1%, 56.0% and specificity of 44.8%, 65.2%, 72.8% for diagnosis of SSc at different cutoff values respectively (signal intensities 1+, 2+ and 3+). An overall diagnosis performance of AUC 0.674, 65.36% accuracy, 36.36% positive predictive value (PPV), 86.18% negative predictive value (NPV), 1.89 positive likelihood ratio (LR+), 0.53 negative likelihood ratio (LR-) was determined at the optimal cutoff of 2+. For SSc patients, we observed significantly higher risk of diffuse-type scleroderma in participants with negative autoantibodies, anti-Scl-70, anti-RNA polymerase III and anti-Ro-52 positive (OR: 12.28, 95% CI: 3.19-47.19, p &lt;0.001; OR: 33.56, 95% CI:8.91-126.51, p &lt;0.001; OR:18.32, 95% CI:4.16-80.71, p &lt;0.001; OR:2.00, 95% CI:1.05-3.83, p=0.036, respectively, Table1) as compared to the counterparts. Development of ILD was more frequently seen in SSc patients with autoantibody negative, anti-Scl-70, and anti-Ro52 positive (OR: 8.48, 95% CI: 2.79-25.75, p &lt; 0.001; OR:16.91, 95% CI: 5.61-50.95, p &lt;0.001; OR:2.58, 95% CI: 1.35-4.96, p=0.004, respectively) as compared to counterparts. Anti-Ro52 positive was also associated with PAH and GI tract involvement (OR 3.26, 95% CI: 1.18-8.99, P=0.023; OR: 2.86, 95% CI: 1.28-6.39, p=0.011). In addition, we found combination of anti-Scl-70 and anti-Ro52 positive was associated with the highest rate of ILD (Figure 1). <h3>Conclusion</h3> We demonstrated the diagnostic performance of LIA in Taiwanese patients with optimal cutoff defined and also the prognostic values of autoantibodies. Moreover, anti-Ro52 was associated with higher risk of various organs involvement including ILD, PAH and GI tract involvement. <h3>References</h3> [1]Y, Simms R, Distler O, Trojanowska M, Pope J, Denton CP, Varga J. Systemic sclerosis. Nat Rev Dis Primers. 2015 Apr 23;1:15002. doi: 10.1038/nrdp.2015.2. PMID: 27189141. <h3>Acknowledgements</h3> We thank the Biostatistics Task Force of Taichung Veterans General Hospital for assisting with the data analysis. <h3>Disclosure of Interests</h3> None Declared.